The improvements constantly being achieved in the field of information supports and playback/recording heads allow the information density to be doubled almost every three to four years. Thus, units are able to be more compact by utilizing heads of smaller sizes. As a result, foreign matter such as dust, impurities, smoke, water vapor, and conditions of high humidity, which was tolerated with larger size playback/recording heads, when deposited on smaller size heads, may hamper their performance or partially shut them off with the result of playback or recording of poor quality.
To overcome such drawback, a cleaning means has been proposed for playback/recording heads, such as described in U.S. Pat. No. 5,170,304, which is made temporarily operative upon switching the unit on. Nevertheless, such cleaning means are not satisfactory because, being integrated within the unit, they are only accessible with great difficulty and, accordingly, changing or servicing them is almost impossible although such should be regularly performed. In addition, they cannot prevent accumulation or deposit of foreign matter, particularly particles.
Applicant has also proposed, as disclosed in U.S. Pat. No. 4,519,059, elements covering the play-back head during a cleaning of the data support but this protection is temporary, being operative during a cleaning operation.
Japanese Patent Application 51-111500 discloses a device preventing a data support from being over exposed to the beam of a laser in the absence of recording by a shutter driven by an electromagnet. Such a device protects the support, not the head, and cannot be used in the vicinity of a magnetic or optical head because of the magnetic flux generated by the electromagnet; further, shielding of the head is unwise as being an expensive solution which further adds weight to a mobile element which should stay as light as possible.
German Application DE 195 23 785 discloses a rather large device shielding the playback head and further requires that the head be systematically powered back to a predetermined position (the lead-in track of the disc), which is burdensome and prohibits resuming playback instantaneously from the position where play mode has been interrupted. In addition, this specific movement is hardly possible in car units because switching off the car engine by the key turns off all power sources/lines to the playback/recording apparatus and, thus, no powered movement can be performed afterwards.